Stereoscope



Patented` June 8, 1937 `UNITED STATES :Sassi:

.ziiiiil3 PATENT OFFICE srsanoscors John B. N. Cardona, New York, N. Y.,.asaignor of one-half to Wilton Bentley, New York, N. Y.

Application June 25, 1934, Serial No. '132,350

5 Claims. (Cl. 88-29) l 5 view that is a mental composite arising from diil'erences in angle oi view in the individual pictures. To this stereoscopic impression it is desirable to introduce an improved balance of relative tone values, and particularly a faithful .lo rendering of color. y

An object of this invention, thereforeyis to provide means ior beholding colon in stereoscopic photographs. A further object is to obtain such color impressions or relative tone values by means that are simple, or suitable ior inexpensive manuiacture in quantities and suitable for use even by children. A further object is to provide color control means that are adaptable to existing stereoscopic viewing apparatus. z A particularly important object of this invention is to provide means for altering or adjusting the eilfectvy of color at will in viewing stereoscopic pictures, so as to overcome various conditions of physical and physiological nature that contribute 5 to the iinal composite-impression from the stereoscopic pictures. These and other objects will be apparent from the following speciiic descrip- Y tion and accompanying drawing illustrative this invention.

In the drawing. li'ig. 1 represents a stereoscopic viewing apparatusthat combines means according to'this invention for altering or controlling color impressions oi stereoscopic views. Fig. 2 illustratescharacteristics or ranges of color oi' typical color illters for use vin a stereoscopic viewingapparatus. Figs. 3 and 4 illustrate 'modiiications oi this invention for varying. stereoscopic color impressions, while Fig. 5 illustrates another modiilcation oi this invention. Figs. 6 o and '7 illustrate a further embodiment of the principles of this invention for color control.

This inventionis predicated onrny discovery that in stereoscopic viewing'pf images that con-v tain in vid diiierences ot tone. composite imof lor variation may be eilected in simple manner by regulating the relative intensity,which. also is regulation of -eiiective quality o! light for the individual images. For illustration a preferred arrangement is described herein 50 in which black ma 'nin-image.. saving insa vidual dinerencesoi density as color-.correction an `viewed stereoseopically through complemenfvtarycolornltersrespectivelmwithmeanstovary ,the relative intensity of light reaching the eyes iran the color illtei's.v .In brief, this-invention contemplates improvements in controlling or varying the psychological ror effective color reception from a pair 'of stereoscopic images. Preferablyythe relative intensity or differential illumination of the images is varied. 5

iReferring more particularly to the drawing for purposes oi specific 'illustration oi this invention, Fig. 1 depicts a stereoscopic I which houses viewing lenses 2 and l, and slots or a guideway l, l for holding a pair oi stereoscopic pictures be- 10 fore thel respective lenses. The form illustrated is adapted to view illms byl light transmitted through diilusion glassest, l. lEach beam of light through the individual pictures traverses a color screen, respectively illustrated as l and 9. 15

Ordinarily these color screens yield color bands Athat are generally complementary to each. other.

The pictures being viewed are intended to be printed with corresponding color corrections or 'local differences oi intensity from -each other.-

'I'hus an object correctedand printed in the one picture of different localy intensity or transparency from its print in the companion picture, when viewed solely through a red color filter would appear generally red where red'in the orig- 25 inal object; while its companion picture when viewed solely through a green color iilter would appear generally green where green in the original object.A However, when. the two pictures are' viewed simultaneously' through the respective 30 iiltera in the stereoscope the composite impresf sion' should be a blend that contains the two colors'in proportion properly to represent the o 'rig-v inal colorappearance of the object. Any number of color objects'may thus be viewable in prop- 3'5 er tonebalance. In ultimate form'this presupposes that the density or opacity oi the respective color illters be selected or varied to convey more or less o! the one color or the other contributing to the general, composite impression oi the stereoscope' pictures. j

With a series v of dinerent views, or with diiferent persons observing the views, or with different conditions oi Vlight for observing tli|e-views, one picture may appear as a pleasing natural 45 color image, but4 others may appear to contain incongruous color variations from the na image. Attempts toreproduce natural views in the visual perceptionof different persons involve at least linie-independently variable conditions. Thus, dierences between the photographs themselves arise from diu'ercnces in the spectrum oi light in which the ohiect'is photographed and A also from immenses or intensity or mit light;

while further differences arisein the images from 5a are viewed and from diuerent intensities of that light. Finally are encountered visual idiosyn;

crasi'es of` diilerent persons viewing the photographs.

This'invention involves means in a streoscope for correcting impressions, of color in the stereoscope beams reaching the eyes of a beholder. Natural objects, art pictures and the like may aplo pear pleasing and natural to dierentpersons and under dide'ring light conditions. l

Fig. 2 represents the color ranges of a given pair-of lters. More accurately Fig. 2 illustrates that a given filter transmits a band of color or l5 range of wave lengths of light. Thus a certain tone of red, as shown, transmits practically no light of the shorter wavelengths. But from wave lengths oi* approximately 5506 Angstrom units (Af) to above approximately 70d@ A? its transmission is emcient and extensive. A certain tone vof green, as shown, transmits effectivelxrthe light oi wave lengths between aboutdi) Af and 6500 A?. and also oi about 'lcil Af. Thus a certain balance, or characteristic color tone, is presented by each pair of color filters. f

However, the stereoscopic color impression may be corrected in simple manner.

Thus in Fig. 3 is shown a pair of colorless light screens lo, li, each varying in opacity from one end to the other. These screens may be of glass, or Aof cellulosic lm base, or of other suitable material.- The screens are adapted to be inserted between the light sources and the stereoscopic lenses. as for example in slot d, 9 of Fig. 1. I n.

this latter example the color illters may, if desired, be combined with the ground glasses and l. The variations in opacity of screens it, i l may be opposed and progressive, as shown, or may be as a series oi distinct areas of differing intensity.

`y The screens-,may be separated and moved independently, or a single screen of varying intensity may be used, but as shown an interdependent pair is adapted to be moved simultaneously across the elds. They provide extensive variation in theA 45.proportions ofiight transmitted from the respective filters. Nevertheless the balanceof wave lengths from 'each lter, or the tone of color transmitted by each, remains unchanged. Howl ever the adjustment is dierential and compositey color impression received from both through thestereoscope isthus varied in simple manner.

' In the modication shown in Fig. 4, a pair of suitable light screens I 2 and i3, of glass, cellulosic'llm base or other suitable material, not only .55 varies in density over dierent areas but is suitably coloredas well. Thus this screen may be' used, if desired. to replace not only density screens lilv and Il of Fig. 3, butto replace the color illtersas well.v Such variations maybe brought aboutv by 'increasing layers Aoi colored material or by increasing densityofi-.colorant therein.. 0r, such colored'screens as Iffand i3 may be used with -given separate color lters and-may be selected o? such color qualities as to absorb selected wave lengths from certain areas of the predominant color filters. Where screens I2' and I3 are tinted 'but slightly they have the chassis the spectrum of light in which the photographs' be regarded as a section across the stereoscope tubes shown in Fig. i. t

In the modication shown in Fig. 5, dis.- phragms id and l5 of variable openings are interposed in the tubes to diminish the intensity oi each of the colored beams from the 'respectivev pictures. As shown, each diaphragm is independly adjustable. The eect is to vary the composite color impression in the stereoscopic image.

For further illustration of the principles ci this invention, reference is had to Figs. 6 and 7. Eig. 7 is an end view exposed at substantially the line 'i-l of Fig. 6. In this modcation variation of the stereoscopic color image is obtained by utilizing individual light sources, from which the light is independently varied. In the form shown, the illustration of av transparent hlm heretofore used in this specication is continued. The stereoscope housing i is as shown in Fig. 1, with the similar slots l and 5f for the nlm pictures. Ground glasses d, i or other diusing means is mounted between the lm and the iight source. In this modification, as indeed in theother modifications, the di'using screens may also 'ce colored 'suitably to serve as color lters.J In this present;

form of the invention, a magazine ib is attached `in front of the diusing screen, so as to hold a light source, such as small electric bulbs ii and it?, before each ground glass. I have found bulbs of ash light type to be suitable. 'line magazine also contains suitable energizing means, such as small dry cell i9. Contained also in the niagazine are means for independently controlling the intensity of each light. Thus, as shown, bulbs il, ld may be inserted through metal stripsd, 2 i,

which also serve as parallel conductors between the lamps and the cell It. The circuit may be completed, and further support afforded for the f lamps, by metal strip 22 which extends across the housing is. 'Ihe middle portion of strip 22 is bent to aiord spring contact with one pole oi cell is.

As shown in Fig. 7, one branch 2i oi' the parallel connectors comprises a rheostat 23 or other variablev resistance so that the intensity of the two lamps may be altered relatively to each other.

The eiect of varying the intensity of the lam,Y

to alter the composite colorY impression in the' stereoscopic image from the two viewing lenses. It is within the purview of this invention te introduce color from the lampsif desired,'a'nd to Vuse these lamps in conjunction with other modifica.-V tions of this invention, such as the modifications herein illustrated. A

Various alterations will occur within the scope of this invention and the appended claims. For example, these principles may be Yextended not only to stereoscopic structure for viewing transparent pictures, but also to such as are suitable forV viewing pictures by reiiected light.

Advantagesof this invention will be apparent l on consideration that the intimate composite impression of color in a stereoscopic' view is'complex, and subject to many variable.. conditions.

`I .ior example, 'in making the original negatives as welles in printing the positives for viewing, the photographic emulsions vary according to the sources, batches of emulsion from the same manufacturer. This is particularly true where accurate color rendering is sought. Moreover. color filters -used either in photographing :negatives or in -viewing the positives exhibit variations in the colorv transmitted. Also, the light and other facteY and evenVA according'to diierent tors of exposure of the negative introduce dier- Q5 ences between otherwise similar views, when the color is considered. Particularly important is the fact that different human beings who use the stereoscope differ in sensitiveness to given color stimuli, and therefore without means for color control individuals would View a given stereoscopic picture with differing color eiects. Even the eyes of a given person diier from time to time as to color response. Also the light for viewing stereoscopic pictures varies, as for example from reflection by one surface or another to the pictures being viewed. The present invention meets these complex and Variable conditions in simple manner.

According to the provisions of the patent statutes, I have explained the principle and mode of operation of my invention, and have illustrated and described what I now consider to represent its best embodiments. However, I desire to have l0 it understood that, within the scope of the appended claims, the invention-may be practiced otherwise than as specifically illustrated and described.

I claim:

1. In combination, a pair of stereoscopic pictures in which the separate pictures record different colors of an object, a stereoscope for viewing the pictures, means to illuminate the pictures, means to vary the intensity of illumination of the 30 respective beams from the two pictures and means to impart diierences of color to the separate beams from the pictures.

2. In combination, a pair of stereoscopic pictures-in which the separate pictures record com- 35 plementary diiierences of color of an object, a

stereoscope for viewing the pictures, means to illuminate the pictures, means to vary the intensity of illmnination of the respective beams from.

the two pictures progressively and inversely to each other, and means to impart to the separate 'beams from the pictures complementary diierences of color corresponding to the respective pictures.

3. In combination, a pair of stereoscopic pictures in which the separate pictures record complementary differences of color of an object, a stereoscope for viewing the pictures, means to illuminate the pictures, means to vary the intensity of illumination of the respective beams from the two pictures simultaneously and inversely to each other, and means to impart to the separate beams from the pictures complementary dinerences of color corresponding to the respective pictures.

4. In combination, a pair of stereoscopic plctures in which the separate pictures record complementary diierences of color of an object, a stereoscope for viewing the pictures, means to illuminate the pictures, and means to impart to the separate beams from the pictures complementary differences of color corresponding to the respective pictures, said coloring means being adapted to vary the intensity of light of the separate beams inversely to each other.

5. In combination, a pair of stereoscopic plctures in which the separate pictures record diierent colors of an object, a stereoscope for viewing the pictures, means to illuminate the pictures,`

means to impart differences of color to the separate beams from the pictures, and means comprising a variable diaphragm to vary the intensity of illumination of the respective beams from the two pictures.

A JOHN B. N. CARDOZA. 

